Part 5: How Do You Find The Stretch Ratio of A Fabric?

The stretch ratio of a knit fabric can be determined by taking a sample of the fabric and measuring it both before and after stretching it.

There are two types of Knits: Weft Knits and Warp Knits.

Step One: Determine if your knit is a weft knit or a warp knit

Weft Knits Examples:

• Jersey
• Sweater knits
• Sweater knits, interlock, rib knit, fleece, knitted terry, velour and sweater knits.

Interlock Knits (have limited stretch in the crossgrain direction), Ribbed knits and bottom-weight double knits (Ponte di Roma, Piqué and jacquard).

Warp Knits Examples:

• Tricot
• Raschel

Step Two: Determine the Direction of Greatest Stretch

When drafting with knits, we want to wrap the body using the greatest stretch direction of the fabric. You must locate the selvadge of your fabric and determine the direction of greatest stretch relative to the selvadge.

For a Weft Knit, in most cases, the direction of greatest stretch will be widthwise and perpendicular to the selvadge (cross-grain).

For a Warp Knit, the direction of greatest stretch will be lengthwise and parallel to the selvadge (Straight Grain)

Step Three: Determine Stretch Ratio Using Hand Elongation

1. Locate the straight grain (warp) of your fabric. The straight grain runs parallel to the selvedge of your fabric.
2. Locate the cross-grain (weft) of your fabric. The cross-grain grain runs perpendicular to the selvedge of your fabric.
3. Measure 5cm perpendicular to the selvadge of your fabric, along the weft/crossgrain of your fabric.
4. Measure 20cm parallel to the selvadge of your fabric, along the warp/grain.
5. Cut out the 20cm x 5cm rectangular strip of fabric according to steps 3 and 4.
6. Place your first pin 5cm in along the 20cm side of the rectangle and place your second pin 10cm from the first pin (the distance between both pins should be 10cm).
7. Place a ruler on your cutting table as a guide when measuring your fabric.
8. Stretch the fabric comfortably. You want to avoid stretching your fabric to the max, stretch your fabric a comfortable amount for wearability.
9. Measure the distance between the pins when the fabric is stretched (For example, the distance between the pins at rest is 10cm and when stretched is 14cm).
10. Enter your fabric length at rest and your fabric length when stretched to calculate negative ease required.
11. If you have the technical sheet for your fabric, you will use the greatest stretch percentage as the average for the fabric.

1. Locate the straight grain (warp) of your fabric. The grain runs parallel to the selvedge of your fabric.
2. Locate the cross-grain (weft) of your fabric. The cross-grain runs perpendicular to the selvedge of your fabric.
3. Measure 20cm perpendicular to the selvadge of your fabric, along the crossgrain.
4. Measure 5cm parallel to the selvedge of your fabric, along the grain.
5. Cut out the 20cm x 5cm rectangular strip of fabric according to steps 3 and 4.
6. Place your first pin 5cm in along the 20cm side of the rectangle and place your second pin 10cm from the first pin (the distance between both pins should be 10cm).
7. Place a ruler on your cutting table as a guide when measuring your fabric.
8. Stretch the fabric comfortably. You want to avoid stretching your fabric to the max, stretch your fabric a comfortable amount for wearability.
9. Measure the distance between the pins when the fabric is stretched (For example, the distance between the pins at rest is 10cm and when stretched is 14cm).
10. Enter your fabric length at rest and your fabric length when stretched to calculate negative ease required.
11. If you have the technical sheet for your fabric, you will use the greatest stretch percentage as the average for the fabric.

← Part 4: What Is The Stretch Ratio Of A Fabric And How Do You Calculate Negative Ease Percentage?

Part 6: How rebound tension and recovery effect fit →